This invention relates to packaging cartons made from multilayer laminates containing paperboard and at least one layer of polymer blends of polyolefins and polyamides.
The most recent improvement in the packaging structure for milk requires a multilayer coextrusion process onto a paperboard substrate as the product contact layer which includes Nylon 6/tie layer/low density polyethylene. This multilayer can be coextruded online and thereby produce a coated substrate. The multilayer coextrusion of Nylon 6/tie layer/low density polyethylene provides oxygen barrier, sealing, strength, and pinhole resistance though it can only be coextruded on very specific coextrusion apparatus.
There is a specific need to develop a barrier material that can be extruded on the product contact side of a paperboard package as a monolayer which has the performance of the multilayer. This approach will produce a lower cost structure verses the multilayer co-extrusion line economics.
According to the present invention, there is provided a polymer blend of a polyamide and a polyolefin, such as Nylon 6 and low density polyethylene, with other required or optional components, that is extruded as a monolayer on the product contact side of a paperboard packaging structure.
The structure improves pinhole resistance as well as oxygen barrier properties over the commercial monolayer structure and produces an improved structure with better bulge resistance via the monolayer extrusion coating process.